“I have been informed with great anguish of Jenny Lumet’s recollection about our night together in 1991,” he said in a statement. “I know Jenny and her family and have seen her several times over the years since the evening she described. While her memory of that evening is very different from mine, it is now clear to me that her feelings of fear and intimidation are real. While I have never been violent, I have been thoughtless and insensitive in some of my relationships over many decades and I sincerely apologize.”

On Nov. 19, The Los Angeles Times reported that Keri Claussen Khalighi, a model who was 17 at the time, had accused Mr. Simmons of coercing her into performing oral sex on him.

“Everything that happened between us 26 years ago was completely consensual and with Keri’s full participation,” Mr. Simmons, 60, said in a statement denying that allegation. “Abusing women in any way shape or form violates the very core of my being.”

In her column, addressed to Mr. Simmons, Ms. Lumet, who was 24 at the time, said Mr. Simmons offered her a ride home from a restaurant, but when she got in the car the doors locked and Mr. Simmons and told the driver to go to his apartment instead of her home address.

She felt threatened, she said, and her focus turned to keeping Mr. Simmons calm, but she never told him that she would go home with him or wished to have sex with him.

“I desperately wanted to keep the situation from escalating,” she said. “I wanted you to feel that I was not going to be difficult. I wanted to stay as contained as I could.”

She said he did not “punch me, drag me or verbally threaten me” when they got to his building, but “used your size to maneuver me, quickly, into the elevator.”

In his apartment, he moved her into a bedroom and did not stop when she said “Wait,” she said.

“At that point, I simply did what I was told,” she said.

Representatives for Mr. Simmons did not respond to requests for further comment.

“As the corridors of power inevitably make way for a new generation, I don’t want to be a distraction so I am removing myself from the businesses that I founded,” he said in a statement. “The companies will now be run by a new and diverse generation of extraordinary executives who are moving the culture and consciousness forward.”

A version of this article appears in print on , on Page A18 of the New York edition with the headline: After Accusations, a Founder of Def Jam Will Resign. Order Reprints | Today’s Paper | Subscribe